I believe it's mainly because korea still is a pretty old fashioned country. You can notice it with the kpop idols ships, they act full gay on screen as long as they generate money but at the moment of actually express their opinion/values they all get neutral and quiet. This drama only works because at the end of the day it's a straight romance, like Mulan
This drama only works because at the end of the day it's a straight romance, like Mulan